Using a rechargeable power source for tape cartridge handling

ABSTRACT

A charge level for a first rechargeable power source, a second rechargeable power source, and a third rechargeable power source is determined. The first rechargeable power source is determined to be below a threshold level of charge. In response to determining that the first rechargeable power source is below a threshold level of charge, a switch is made from the first rechargeable power source to the second rechargeable power source.

BACKGROUND

The present invention relates generally to the field of magnetic tapelibraries, and more particularly to wirelessly handling tape cartridgesin an automated tape library.

Magnetic tape data storage (e.g., an automated tape library) is a systemfor storing digital information on magnetic tape using digitalrecording. Modern magnetic tape is most commonly packaged in cartridgesand cassettes. The tape drive is the device that performs writing orreading of data on the magnetic tape. Autoloaders automate cartridgehandling and provide increased speed for accessing data. Severalcomponents in the cartridge handling system, including the x-y-z driver,x-slider, y-slider, and gripper, are connected via a flat, or ribbon,cable. A common cassette-based format is Linear Tape-Open (LTO). The LTOformat is available in a variety of densities and is manufactured byseveral companies.

SUMMARY OF THE INVENTION

Embodiments of the present invention include a method, computer programproduct, and system for replacing a rechargeable power source in anautomated tape library. In one embodiment, a charge level for a firstrechargeable power source, a second rechargeable power source, and athird rechargeable power source is determined. The first rechargeablepower source is determined to be below a threshold level of charge. Inresponse to determining that the first rechargeable power source isbelow a threshold level of charge, a switch is made from the firstrechargeable power source to the second rechargeable power source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic of an automated tape library, in accordancewith an embodiment of the present invention;

FIG. 2 depicts a schematic of a power-control module within an automatedtape library, in accordance with an embodiment of the present invention;

FIG. 3 depicts a flowchart of a program for replacing a low on powerrechargeable power source, in accordance with an embodiment of thepresent invention;

FIG. 4 depicts a flowchart of a program for retrieving a tape cartridge,in accordance with an embodiment of the present invention; and

FIG. 5 depicts a block diagram of components of a computing environment,in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide for wirelessly handlingtape cartridges in an automated tape library. Current techniques forhandling tape cartridges utilize a flat, or ribbon, cable to providecommunication between the tape library controller, the x-y-z driver, andother components in the tape library. The flat cable is susceptible towear because of the flexing the cable receives while components are inmotion within the tape library to move tape cartridges between storageslots and tape drives, where the tape cartridge is either written to(storing data) or read (retrieving data). The wear to the cable mayresult in errors moving tape cartridges. Consequently, the cable needsto be replaced often.

Embodiments of the present invention recognize that there may be amethod, computer program product, and computer system for wirelesslyhandling tape cartridges in an automated tape library, which mayeliminate the need for the flat cable and the time required to replace aworn cable. Embodiments of the present invention may use a rechargeablepower source to provide power to the following: components within thetape library, charging stations within the tape library that providerecharging power to the rechargeable power sources, and a wirelessnetwork that provides digital communication between the library/chargingnetwork controller and the x-y-z driver/gripper in the library thatmoves the tape cartridges from one location to another within the tapelibrary. Throughout this document, x-y-z will refer to three differentaxes that the driver/gripper assembly can move within the tape library.In an embodiment, “x” will refer to horizontal (i.e., left/right)travel, “y” will refer to vertical (i.e., up/down) travel, and “z” willrefer to depth (i.e., front/back or in/out) travel.

The present invention will now be described in detail with reference tothe Figures.

FIG. 1 is a schematic of an automated tape library, generally designated100, in accordance with one embodiment of the present invention. FIG. 1provides only an illustration of one implementation and does not implyany limitations with regard to the systems and environments in whichdifferent embodiments may be implemented. Many modifications to thedepicted embodiment may be made by those skilled in the art withoutdeparting from the scope of the invention as recited by the claims.

In an embodiment, automated tape library 100 includes frame 1 102A,frame 2 102B, frame 3 102C, frame 4 102D, x-rail 104, x-slider 106,y-rail 108, y-slider 110, tape slot(s) 112, tape drive slot(s) 114, tapedrive(s) 116, gripper 118, x-y-z driver 120, charging network 122,charging station(s) 124, controller 126, access point 128, movementprogram 130, and power-control 202.

In an embodiment, frame 1 102A is the base frame for automated tapelibrary 100. Frame 1 102A is the primary unit of automated tape library100. In an embodiment, frame 1 102A includes components found in allframes of automated tape library 100 including x-rail 104 and y-rail 108(components of the automated tape library 100 rail system), internallighting (not shown), and tape slot(s) 112. In an embodiment, frame 1102A also includes components controller 126, tape drive slot(s) 114,and tape drive(s) 116.

In an embodiment, frame 2 102B, frame 3 102C, and frame 4 102D areexpansion frames, added to base frame 1 102A, to make a four-framelibrary that comprises automated tape library 100. In an embodiment,there are a maximum number of expansion frames, based on the technologyof the tape drive, which can be added to the base frame to comprise thetape library. In an embodiment, frame 2 102B, frame 3 102C, and frame 4102D include common components found in all frames of automated tapelibrary 100 including x-rail 104 and y-rail 108 (components of theautomated tape library 100 rail system), internal lighting (not shown),and tape slot(s) 112. In an embodiment, frame 2 102B, frame 3 102C, andframe 4 102D also include charging network 122 and charging station(s)124.

In an embodiment, x-rail 104 is a component in the rail system found inautomated tape library 100. X-rail 104 allows x-slider 106 to movehorizontally in the base frame and any expansion frames in automatedtape library 100.

In an embodiment, x-slider 106 is a carrier that moves horizontally onx-rail 104 within automated tape library 100. In an embodiment, x-slider106 includes y-rail 108 and x-y-z driver 120. One function that x-slider106 performs is positioning y-rail 108, and consequently gripper 118, inthe correct horizontal position for moving a tape cartridge withinautomated tape library 100.

In an embodiment, y-rail 108 is a component in the rail system found inautomated tape library 100. Y-rail 108 allows y-slider 110 to movevertically in the base frame and any expansion frames in automated tapelibrary 100.

In an embodiment, y-slider 110 is carrier that moves vertically ony-rail 108 within automated tape library 100. In an embodiment, y-slider110 includes gripper 118. One function that y-slider 110 performs ispositioning gripper 118 in the correct vertical position for moving atape cartridge within automated tape library 100.

In an embodiment, tape slot(s) 112 are storage locations for magnetictape cartridges, rechargeable power sources, and charging station(s) 124within automated tape library 100. Both the base frame (frame 1 102A)and the expansion frames (frame 2 102B, frame 3 102C, and frame 4 102D)include any number of tape slot(s) 112. In an embodiment, tapecartridges and rechargeable power sources may be stacked within a tapeslot(s) 112 (i.e., one or more tape cartridge/rechargeable power sourcemay be stored behind the front or first tape cartridge/rechargeablepower source in the tape slot(s) 112).

In an embodiment, tape drive slot(s) 114 are areas within frame 1 102A(the base frame) of automated tape library 100 used for holding tapedrive(s) 116 and charging station(s) 124. In another embodiment, tapedrive slot(s) 114 are areas within frame 2 102B, frame 3 102C, and frame4 102D (the expansion frames) of automated tape library 100 used forholding tape drive(s) 116 and charging station(s) 124. The automatedtape library 100 technology determines the number of tape drive slot(s)114 found in the base frame.

In an embodiment, tape drive(s) 116 are the data storage devices thatread and write data on a magnetic tape cartridge. Magnetic tapecartridges are typically used for offline, archival data storage.Magnetic tape cartridges generally have a favorable unit cost and a longarchival stability. The number of tape drive(s) 116 found in automatedtape library 100 is determined by the number of available tape driveslot(s) 114.

In an embodiment, gripper 118 is an electromechanical device on y-slider110 for moving tape cartridges and batteries within automated tapelibrary 100. Gripper 118 can move a tape cartridge between tape slot(s)112 and tape drive(s) 116. Gripper 118 can also move rechargeable powersources between charging station(s) 124, tape slot(s) 112 andpower-control 202 (to be discussed subsequently). In an embodiment,gripper 118 includes two grabbers that physically grab and hold the tapecartridges or the rechargeable power sources within automated tapelibrary 100. The two grabbers allow gripper 118 to grab the rechargeablepower source powering x-y-z driver 120 that is running low on power witha first grabber, move to charging station(s) 124, grab the rechargeablepower source from charging station(s) 124 with a second grabber, andthen swap the two rechargeable power sources. While the rechargeablepower source swap is occurring, power is being supplied to the system bythe second rechargeable power source in power-control 202, which has ahigher charge than the rechargeable power source in the first grabberthat is being replaced.

In an embodiment, x-y-z driver 120 is the device that facilitates allmotion requests for gripper 118 within automated tape library 100. X-y-zdriver 120 receives input wirelessly from controller 126 via accesspoint 128.

In an embodiment, charging network 122 is an electrical circuit withinautomated tape library 100 that provides power to charging station(s)124 for charging the rechargeable power sources when the rechargeablepower sources are low on power. In an embodiment, charging network 122may be a one hundred twenty volt circuit. In another embodiment,charging network 122 may be a two hundred forty volt circuit.

In an embodiment, charging station(s) 124 is a device, powered bycharging network 122, which recharges the rechargeable power sourcesused by automated tape library 100. In an embodiment, automated tapelibrary 100 includes two charging station(s) 124. In another embodiment,automated tape library 100 includes more than two charging station(s)124. In an embodiment, charging station(s) 124 includes one slot forcharging a rechargeable power source used by automated tape library 100.In another embodiment, charging station(s) 124 includes more than oneslot for charging a rechargeable power source used by automated tapelibrary 100. In an embodiment, when a rechargeable power source is fullycharged by a charging station(s) 124, the rechargeable power source isremoved from the charging station(s) 124 and moved to an empty tapeslot(s) 112.

In an embodiment, controller 126 is a logic card that provides controlfunction to automated tape library 100 and charging network 122. In anembodiment, controller 126 includes access point 128 and movementprogram 130. Functions managed by controller 126 include centralizedmanagement of automated tape library 100, inserting and ejectingoperations for tape cartridges, automatic cleaning of tape drive(s) 116,status determination for automated tape library 100, and powerrequirements for charging network 122 (i.e., provide power to chargingstation(s) 124 when a non-fully charged rechargeable power source ispresent and remove power to charging station(s) 124 when a fully chargedrechargeable power source is present or when charging station(s) 124 isempty).

In an embodiment, access point 128 is a component in a wireless networkcapable of transmitting and receiving data. In an embodiment, accesspoint 128 may provide a connection to a hard-wired network. In anembodiment, access point 128 sends data to power-control 202 whichinstructs x-y-z driver 120 where to move (i.e., tape slot(s) 112, tapedrive(s) 116, or charging station(s) 124). For example, the instructionmay be to retrieve a tape cartridge from a specific tape slot(s) 112 inframe 4 102D and to put the tape cartridge in the first tape drive(s)116 in frame 1 102A so that data can either be written to or retrievedfrom the tape cartridge. In another embodiment, access point 128receives data from power-control 202. In yet another embodiment, accesspoint 128 both sends data to and receives data from power-control 202.In an embodiment, the data transmission is encrypted. In anotherembodiment, the data transmission is not encrypted.

In an embodiment, access point 128 includes movement program 130.According to embodiments of the present invention, movement program 130functions to move tape cartridges and rechargeable power sources withinautomated tape library 100. In an embodiment, movement program 130receives input of an instruction to move a tape cartridge, transmits theinstruction wirelessly using techniques known in the art, directs thegripper mechanism in automated tape library 100 to the proper locationto grab the tape cartridge, and directs the gripper to another locationin automated tape library 100 to place the tape cartridge.

In an embodiment, movement program 130 determines when a rechargeablepower source is low on power and requires swapping for a chargedrechargeable power source stored in charging station(s) 124. In anembodiment, movement program 130 manages the rechargeable power sourceswithin automated tape library 100 (e.g., the location of eachrechargeable power source and the charge level of each rechargeablepower source). In an embodiment, when a rechargeable power source swapis required, the rechargeable power source with the highest charge intape slot(s) 112 or charging station(s) 124 is selected. In anotherembodiment, when a rechargeable power source swap is required, tapeslot(s) 112 or charging station(s) 124 closest to the present locationof x-y-z driver 120 is selected. In yet another embodiment, the currentworkload queue is used to determine which tape slot(s) 112 or chargingstation(s) 124 is used for the rechargeable power source swap (e.g., ifonly one tape cartridge movement is in the queue, any tape slot(s) 112or charging station(s) 124 may be used but if many movements are in thequeue, the tape slot(s) 112 or charging station(s) 124 with therechargeable power source with the highest charge is used for the swap).

FIG. 2 is a schematic of power-control 202, generally designated as 200.In an embodiment, power-control 202 includes tray 204, transceiver 206,rpd slot 1 208, rpd slot 2 210 and rpd cage 212.

In an embodiment, tray 204 is a carrier added to x-y-z driver 120 thatfunctions to hold, in a mechanical manner, rpd cage 212. In anembodiment, tray 204 may also serve as a power pass-through, allowingpower to pass from rpd cage 212 to x-y-z driver 120.

In an embodiment, transceiver 206 is a combination transmitter/receiverof digital signals in a single package. In an embodiment, transceiver206 receives data from access point 128. In another embodiment,transceiver 206 sends data to access point 128 (as shown and describedin FIG. 1). In yet another embodiment, transceiver 206 both receivesdata from and sends data to access point 128. In yet another embodiment,transceiver 206 may send and receive data from one or more othercomponents of FIG. 1. In yet another embodiment, transceiver 206 maysend and receive data from other access points and/or transceivers notshown.

In an embodiment, rpd cage 212 is a rechargeable power device thatprovides power to x-slider 106, y-slider 110, gripper 118, x-y-z driver120, and transceiver 206. In an embodiment, rpd cage 212 includes twoslots—rpd slot 1 208 and rpd slot 2 210. In another embodiment, rpd cage212 may include more than two slots. In an embodiment, each slot in rpdcage 212 (e.g., rpd slot 1 208 and rpd slot 2 210) can hold onerechargeable power source used to provide power. In an embodiment, arechargeable power source held in rpd slot 1 208 and rpd slot 2 210meets the size requirement of fitting into one of the tape slot(s) 112for storage once the rechargeable power source is fully charged. In anembodiment, automated tape library 100 may include any number ofrechargeable power sources. The number of rechargeable power sourcesrequired is based on the number of base and expansion frames included inautomated tape library 100 as well as the anticipated workload forautomated tape library 100. According to embodiments of the presentinvention, each rechargeable power source may be a battery using anybattery technology known in the art (e.g., lithium ion, nickel-cadmium,alkaline, etc.). In another embodiment, each rechargeable power sourcemay be any other rechargeable power source known in the art (e.g., asupercapacitor, etc.) that meets the size requirements of the two ormore slots in rpd cage 212 and meets the power requirements of automatedtape library 100. In addition, each of the two or more slots in rpd cage212 includes the necessary circuitry required to deliver the previouslydiscussed power. In an embodiment, each rechargeable power source in rpdcage 212 includes at least one bar code label to distinguish eachrechargeable power source from a tape cartridge and to differentiate thetwo or more rechargeable power sources from one another.

FIG. 3 is a flowchart of workflow 300 depicting a program for replacinga rechargeable power source based on the charge level of therechargeable power source, in accordance with an embodiment of thepresent invention. In one embodiment, the method of workflow 300 isperformed automatically by movement program 130. In an alternativeembodiment, the method of workflow 300 may be initiated at the requestof a user.

In an embodiment, movement program 130 determines the charge (step 302).In other words, movement program 130 determines the charge of each ofthe two or more rechargeable power sources found in rpd cage 212. In anembodiment, the charge is a measure of remaining power stored in therechargeable power source. In an embodiment, any technique known in theart, such as a Coulomb counter, can be used to determine therechargeable power source charge. For example, rechargeable power source“A” in rpd slot 1 208 has a charge of eight percent and rechargeablepower source “B” in rpd slot 2 210 has a charge of ninety-five percent.

In an embodiment, movement program 130 determines whether the charge inany of the two or more rechargeable power sources found in rpd cage 212has reached a threshold (decision step 304). In other words, movementprogram 130 determines whether a rechargeable power source is runninglow on power (i.e., reached a threshold level of charge) and needs to bereplaced. In an embodiment, the threshold may be defined by a user. Inanother embodiment, the threshold may be calculated by movement program130 based on the number of tape retrievals during the life of arechargeable power source. In the embodiment, the life of a rechargeablepower source is determined by an average duration of a plurality ofrechargeable power sources. In an embodiment (decision step 304, NObranch), a rechargeable power source has not reached a threshold levelof charge; therefore, movement program 130 continues to determine thecharge of each of the two or more rechargeable power sources. In theembodiment (decision step 304, YES branch), a rechargeable power sourcehas reached a threshold level of charge; therefore, movement program 130proceeds to step 306.

In an embodiment, movement program 130 switches rechargeable powersource (step 306). In other words, responsive to determining that arechargeable power source has reached a threshold level of charge(decision step 304, YES branch), movement program 130 switches thesource of power. In an embodiment, movement program 130 switches therechargeable power source from the rechargeable power source located inrpd slot 1 208 to the rechargeable power source located in rpd slot 2210. For example, given an example threshold of ten percent,rechargeable power source “A”, with a charge of eight percent, is takenout of service (i.e., is no longer powering a portion of the automatedtape library) and rechargeable power source “B”, with a charge ofninety-five percent, is placed into service so that the necessary powerrequirements are provided by rechargeable power source “B”.

In an embodiment, movement program 130 replaces the rechargeable powersource (step 308). In other words, following the switch in rechargeablepower source (step 306), movement program 130 replaces the low-on-powerrechargeable power source with a charged rechargeable power source. Inan embodiment, the charged rechargeable power source selected to replacethe low-on-power rechargeable power source is located in tape slot(s)112 or charging station(s) 124 closest to the present location ofpower-control 202. In another embodiment, the charged rechargeable powersource selected to replace the low-on-power rechargeable power source isthe rechargeable power source found in tape slot(s) 112 or chargingstation(s) 124 with the highest charge level. In yet another embodiment,the charged rechargeable power source selected to replace thelow-on-power rechargeable power source is chosen based on the remainingworkload (i.e., the remaining number of needed movements) in theinstruction queue. For example, rechargeable power source “A”, with acharge of eight percent, is replaced with a rechargeable power sourcefrom one of the charging stations with a charge of ninety-nine percent.

FIG. 4 is a flowchart of workflow 400 depicting a program for moving atape cartridge based on an instruction, in accordance with an embodimentof the present invention. In one embodiment, the method of workflow 400is performed automatically by movement program 130 based on one or moreinstructions received from another computing device. In an alternativeembodiment, the method of workflow 300 may be initiated by a userinputting instructions directly to automated tape library 100.

In an embodiment, movement program 130 receives a request (step 402). Inother words, movement program 130 receives a request, from a user, tomove a tape cartridge from tape slot(s) 112 to a tape drive(s) 116 sothat data may be retrieved from the tape cartridge. In an embodiment, auser inputs a request to retrieve data stored to a tape cartridge usingan integrated management console (not shown) on automated tape library100. In the embodiment, the request is received by controller 126, whichidentifies and locates the specific tape cartridge where the requesteddata is stored. For example, “Joe” inputs a request to retrieve companytax records, stored to tape, from the last twenty-five years. The tapelibrary determines that the requested data is stored to a tape cartridgeidentified as “TAXREC-HISTORY”via a barcode and that the tape cartridgeis stored in slot “Row 3/Column 3” in the first expansion frame in thetape library.

In an embodiment, movement program 130 wirelessly transmits theinstruction (step 404). In other words, based on the received request(step 402), movement program 130 wirelessly transmits the instructionrequired to carry out the request. In an embodiment, controller 126inputs the determined tape cartridge location to access point 128, whichtransmits the instruction to retrieve the tape cartridge to transceiver206. In an embodiment, the transmission is encrypted to prevent anyoneelse from determining the transmission. In the embodiment, theencryption technique is any encryption technique known in the art. Inanother embodiment, the transmission is not encrypted. For example, theinstruction to retrieve the “TAXREC-HISTORY” cartridge stored in slot“Row 3/Column 3” in the first expansion frame of the tape library istransmitted with encryption from the tape library controller to thepower-control module.

In an embodiment, movement program 130 receives the instruction (step406). In other words, movement program 130 receives the transmittedinstruction (step 404) to retrieve a tape cartridge. In an embodiment,the instruction is received by transceiver 206, which is a component ofpower-control 202. In turn, power-control 202 passes the instruction tox-y-z driver 120 so that the cartridge can be moved from tape slot(s)112 to tape drive(s) 116 via gripper 118. For example, the instructionto retrieve the “TAXREC-HISTORY” cartridge stored in slot “Row 3/Column3” in the first expansion frame of the tape library is received by thepower-control module and is then passed to the x-y-z driver.

In an embodiment, movement program 130 executes the instruction (step408). In other words, the received instruction (step 406) to retrieve atape cartridge is executed by movement program 130. In an embodiment,x-y-z driver 120 positions gripper 118 by moving x-slider 106horizontally along x-rail 104 and y-slider 110 vertically along y-rail108 until gripper 118 is in the proper position to grab the requestedtape cartridge. In the embodiment, gripper 118 grabs the requested tapecartridge and holds it while x-y-z driver 120 moves the gripper intoposition at tape drive(s) 116 so that the tape cartridge can be insertedinto the tape drive(s) 116 and the data stored to the tape cartridge canbe read. For example, the gripper is moved to slot “Row 3/Column 3” inthe first expansion frame in the tape library so that the gripper cangrab tape “TAXREC-HISTORY” stored in that slot. The gripper is thenmoved to an open tape drive where the tape cartridge is inserted intothe open tape drive and the tax records are read and made available to“Joe”.

FIG. 5 depicts computer system 500, which is an example of a system thatincludes movement program 130. Computer system 500 includes processors501, cache 503, memory 502, persistent storage 505, communications unit507, input/output (I/O) interface(s) 506 and communications fabric 504.Communications fabric 504 provides communications between cache 503,memory 502, persistent storage 505, communications unit 507, andinput/output (I/O) interface(s) 506. Communications fabric 504 can beimplemented with any architecture designed for passing data and/orcontrol information between processors (such as microprocessors,communications and network processors, etc.), system memory, peripheraldevices, and any other hardware components within a system. For example,communications fabric 504 can be implemented with one or more buses or acrossbar switch.

Memory 502 and persistent storage 505 are computer readable storagemedia. In this embodiment, memory 502 includes random access memory(RAM). In general, memory 502 can include any suitable volatile ornon-volatile computer readable storage media. Cache 503 is a fast memorythat enhances the performance of processors 501 by holding recentlyaccessed data, and data near recently accessed data, from memory 502.

Program instructions and data used to practice embodiments of thepresent invention may be stored in persistent storage 505 and in memory502 for execution by one or more of the respective processors 501 viacache 503. In an embodiment, persistent storage 505 includes a magnetichard disk drive. Alternatively, or in addition to a magnetic hard diskdrive, persistent storage 505 can include a solid state hard drive, asemiconductor storage device, read-only memory (ROM), erasableprogrammable read-only memory (EPROM), flash memory, or any othercomputer readable storage media that is capable of storing programinstructions or digital information.

The media used by persistent storage 505 may also be removable. Forexample, a removable hard drive may be used for persistent storage 505.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer readable storage medium that is also part of persistent storage505.

Communications unit 507, in these examples, provides for communicationswith other data processing systems or devices. In these examples,communications unit 507 includes one or more network interface cards.Communications unit 507 may provide communications through the use ofeither or both physical and wireless communications links. Programinstructions and data used to practice embodiments of the presentinvention may be downloaded to persistent storage 505 throughcommunications unit 507.

I/O interface(s) 506 allows for input and output of data with otherdevices that may be connected to each computer system. For example, I/Ointerface 506 may provide a connection to external devices 508 such as akeyboard, keypad, a touch screen, and/or some other suitable inputdevice. External devices 508 can also include portable computer readablestorage media such as, for example, thumb drives, portable optical ormagnetic disks, and memory cards. Software and data used to practiceembodiments of the present invention can be stored on such portablecomputer readable storage media and can be loaded onto persistentstorage 505 via I/O interface(s) 506. I/O interface(s) 506 also connectto display 509.

Display 509 provides a mechanism to display data to a user and may be,for example, a computer monitor.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment of theinvention. However, it should be appreciated that any particular programnomenclature herein is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method for replacing a rechargeable powersource in an automated tape library, the method comprising: determining,by one or more computer processors, a charge level for a firstrechargeable power source, a second rechargeable power source, and athird rechargeable power source of a plurality of rechargeable powersources in an automated tape library; and responsive to determining thata charge level for the first rechargeable power source is below athreshold level of charge, switching, by one or more computerprocessors, from the first rechargeable power source to the secondrechargeable power source in the automated tape library.
 2. The methodof claim 1, further comprising: replacing, by one or more computerprocessors, the first rechargeable power source with the thirdrechargeable power source in the automated tape library.
 3. The methodof claim 1, wherein the third rechargeable power source is selected fromthe group consisting of a rechargeable power source closest to the firstrechargeable power source, a rechargeable power source with a highestlevel of charge, and a rechargeable power source able to perform aremaining workload in an instruction queue in the automated tapelibrary.
 4. The method of claim 1, wherein the threshold level of chargeis defined from the group consisting of by a user and by a number oftape retrievals during a life of the rechargeable power source, whereinthe life of the rechargeable power source is determined by an averageduration of a plurality of rechargeable power sources.
 5. The method ofclaim 2, wherein a location of the third rechargeable power source inthe automated tape library is selected from the group consisting of atape slot in a plurality of tape slots in the automated tape library ora charging station in a plurality of charging stations in the automatedtape library.
 6. The method of claim 1, further comprising: receiving,by one or more computer processors, an indication to remove the thirdrechargeable power source from one charging station of the plurality ofcharging stations; and sending, by one or more computer processors, arequest to place the third rechargeable power source in one tape slot ofthe plurality of tape slots for storage.
 7. The method of claim 2,wherein the step of replacing, by one or more computer processors, thefirst rechargeable power source with the third rechargeable powersource, comprises: receiving, by one or more computer processors, afirst instruction to move the first rechargeable power source from afirst slot a rechargeable power device to an empty charging station orto an empty tape slot; and receiving, by one or more computerprocessors, a second instruction to move the third rechargeable powersource, from a charging station with the third rechargeable power sourceor a tape slot with the third rechargeable power source, to the firstslot in the rechargeable power device.
 8. A computer program product forreplacing a rechargeable power source in an automated tape library, thecomputer program product comprising: one or more computer readablestorage media; and program instructions stored on the one or morecomputer readable storage media, the program instructions comprising:program instructions to determine a charge level for a firstrechargeable power source, a second rechargeable power source, and athird rechargeable power source of a plurality of rechargeable powersources in an automated tape library; and responsive to determining thata charge level for the first rechargeable power source is below athreshold level of charge, program instructions to switch, from thefirst rechargeable power source to the second rechargeable power sourcein the automated tape library.
 9. The computer program product of claim8, further comprising program instructions stored on the one or morecomputer readable storage media, to: replace the first rechargeablepower source with the third rechargeable power source in the automatedtape library.
 10. The computer program product of claim 8, wherein thethird rechargeable power source is selected from the group consisting ofa rechargeable power source closest to the first rechargeable powersource, a rechargeable power source with a highest level of charge, anda rechargeable power source able to perform a remaining workload in aninstruction queue in the automated tape library.
 11. The computerprogram product of claim 8, wherein the threshold level of charge isdefined from the group consisting of by a user and by a number of taperetrievals during a life of the rechargeable power source, wherein thelife of the rechargeable power source is determined by an averageduration of a plurality of rechargeable power sources.
 12. The computerprogram product of claim 9, wherein a location of the third rechargeablepower source in the automated tape library is selected from the groupconsisting of a tape slot in a plurality of tape slots in the automatedtape library or a charging station in a plurality of charging stationsin the automated tape library.
 13. The computer program product of claim8, further comprising program instructions stored on the one or morecomputer readable storage media, to: receive an indication to remove thethird rechargeable power source from one charging station of theplurality of charging stations; and send a request to place the thirdrechargeable power source in one tape slot of the plurality of tapeslots for storage.
 14. The computer program product of claim 9, whereinthe program instruction to replace the first rechargeable power sourcewith the third rechargeable power source in the automated tape library,comprises: program instructions to receive a first instruction to movethe first rechargeable power source from a first slot a rechargeablepower device to an empty charging station or to an empty tape slot; andprogram instructions to receive a second instruction to move the thirdrechargeable power source, from a charging station with the thirdrechargeable power source or a tape slot with the third rechargeablepower source, to the first slot in the rechargeable power device.
 15. Acomputer system for replacing a rechargeable power source in anautomated tape library, the computer system comprising: one or morecomputer processors; one or more computer readable storage media; andprogram instructions stored on the one or more computer readable storagemedia for execution by at least one of the one or more computerprocessors, the program instructions comprising: program instructions todetermine a charge level for a first rechargeable power source, a secondrechargeable power source, and a third rechargeable power source of aplurality of rechargeable power sources in an automated tape library;and responsive to determining that a charge level for the firstrechargeable power source is below a threshold level of charge, programinstructions to switch, from the first rechargeable power source to thesecond rechargeable power source in the automated tape library.
 16. Thecomputer system of claim 15, further comprising program instructionsstored on the one or more computer readable storage media for executionby at least one of the one or more computer processors, to: replace thefirst rechargeable power source with the third rechargeable power sourcein the automated tape library.
 17. The computer system of claim 15,wherein the third rechargeable power source is selected from the groupconsisting of a rechargeable power source closest to the firstrechargeable power source, a rechargeable power source with a highestlevel of charge, and a rechargeable power source able to perform aremaining workload in an instruction queue in the automated tapelibrary.
 18. The computer system of claim 15, wherein the thresholdlevel of charge is defined from the group consisting of by a user and bya number of tape retrievals during a life of the rechargeable powersource, wherein the life of the rechargeable power source is determinedby an average duration of a plurality of rechargeable power sources. 19.The computer system of claim 16, wherein a location of the thirdrechargeable power source in the automated tape library is selected fromthe group consisting of a tape slot in a plurality of tape slots in theautomated tape library or a charging station in a plurality of chargingstations in the automated tape library.
 20. The computer system of claim15, further comprising program instructions stored on the one or morecomputer readable storage media for execution by at least one of the oneor more computer processors, to: receive an indication to remove thethird rechargeable power source from one charging station of theplurality of charging stations; and send a request to place the thirdrechargeable power source in one tape slot of the plurality of tapeslots for storage.